Lewis & Short

cēÿx, ȳcis, m., = κήϋξ, the male kingfisher (the female, halcyon), Plin. 32, 8, 27, § 86.
Personified: Cēyx, ȳcis, m., = Κήϋξ, a son of Lucifer, king of Trachis, and husband of Alcyone. Having suffered shipwreck at Delphi, he and his wife were changed to kingfishers, Ov. H. 17 (18), 81; id. M. 11, 272; 11, 544; 11, 739; Serv. ad Verg. G. 1, 399.
Acc. Gr. Cēȳca, Ov. M. 11, 727.